水耦合装药对露天深孔爆破效果影响的探讨

介绍了某露天山坡矿采用水耦合装药爆破技术,通过与常规爆破对比试验分析,提出利用水耦合爆破可以改善露天深孔爆破效果、提高原矿大块合格率和降低炸药单耗,达到安全增效、降耗的目的。     

Method of calculating the collision integral and solution of the Boltzmann kinetic equation for simple gases,gas mixtures and gases with rotational degrees of freedom

The conservative method of calculating the Boltzmann collision integral for simple gases, gas mixtures and gases with rotational degrees of freedom of molecules is presented. In all cases the common approach based on the projection technique of summing up the contributions in the collision integral is used. The method is applied for solving the Boltzmann kinetic equation for two fundamental rarefied gas flow problems: the heat transfer problem and the problem of shock wave structure. A comparison with experimental and numerical data of other authors is reported. It is shown that the considered numerical method allows one to solve the Boltzmann equation for real gases with high accuracy.     

单足机器人垂直跳跃动态特性研究

单足机器人一个跳跃周期经历触地相和腾空相两种约束状态,针对机器人触地相落地碰撞、缓冲、起跳,腾空相起跳冲击和伺服定位各过程,综合应用动力学、热力学、流体力学、碰撞和控制理论等建立了机器人一个跳跃周期的综合数学模型.在Matlab上建立了机器人一个跳跃周期的联合仿真模型,对影响单足机器人落地碰撞、起跳冲击和跳跃高度的主要因素进行了仿真研究,得出了实现机器人增高跳跃、减高跳跃和等高跳跃时各影响因素的取值范围和较佳值,包括机器人落地时刻气缸下腔气压预设值和活塞相对坐标预设值,起跳过程气缸充排气转换相对坐标等因素影响跳跃高度、落地碰撞和起跳冲击的规律性认识.搭建了单足机器人垂直跳跃实验台,针对各主要影响因素对机器人跳跃过程的影响规律进行了实验研究,实验结果与仿真数据吻合良好.     

软启动器在煤矿大采高工作面中的应用研究

介绍了神华乌海能源有限责任公司大采高工作面的供电方案及设备配套,研究了软启动器在刮板输送机中应用的可行性,重点分析了使用软启动器之后采区负载启动时对移动变电站的电气冲击情况。使用Matlab/Simulink软件建立采区供电系统模型,对软启动器的启动性能进行仿真分析,在轻载时使用限流启动方式,在重载时使用变频启动方式,结果表明软启动器能有效降低设备启动时的电气冲击。     

镱应力传感器的制作与应用

在数十MPa~2 GPa范围内的动态应力测量中,镱传感器的压阻系数高,可灵活埋置于待测材料中使用。该种传感器对研究冲击波在岩石、土壤、液体介质和结构材料中的传播与衰减规律显示出了优异性能。对国内外镱应力传感器研制工作进行了总结,介绍了该类传感器在爆炸、射弹侵彻、高速碰撞以及高能激光辐照等方面的应用,并指出了该种传感器存在的一些问题。     

A new optical elasticity resin for mobile LCD modules

Abstract— The display used in current cell phones has an air gap between the cover glass and the liquid‐crystal‐display (LCD) module to prevent the LCD glass from being damaged. Reflections at the boundaries of the air gap cause a reduction in the LCD luminance and contrast. To address this problem, a newly proposed LCD structure has been investigated. The “Super View Resin (SVR),” a transparent elastic resin which improves the shock resistance and visibility of the LCD, has been developed. Filling the air gap between the cover glass and LCD module with a refractive‐index‐matching resin solves the light‐reflection problem inherent in the use of a reinforced cover‐glass lens. Moreover, the elastic filler works as a damper, reducing any external shock, which prevents not only the cover glass and LCD module from being damaged, but also the glass from being shattered when it is broken.     

Reliability analysis on systems with self-healing and self-repairing under different environments and shock models

Inspired by the process of self-healing of biological damage, high technology materials with self-healing and self-repairing mechanisms have been developed for high reliability and long lifetime. Therefore, the reliability modeling on intelligent systems with healing performance has become a research hotspot. Based on the diversity of healing mechanisms, this paper proposes a two-phase reliability model method on self-healing and self-repairing systems. Impacts of environments, shock loads, self-healing, and self-repairing mechanisms are taken into account in this novel model. Besides, system lifetime and some reliability indexes under two shock models are derived, respectively. Moreover, Monte Carlo simulations are conducted to verify the accuracy of reliability under two models. Finally, an engineering case of metallized film capacitor is provided to illustrate the effectiveness and applicability of the proposed models by comparing numerical results and simulation results.     

Application of partial mutual information variable selection to ANN forecasting of water quality in water distribution systems

Recent trends in the management of water supply have increased the need for modelling techniques that can provide reliable, efficient, and accurate representation of the complex, non-linear dynamics of water quality within water distribution systems. Statistical models based on artificial neural networks (ANNs) have been found to be highly suited to this application, and offer distinct advantages over more conventional modelling techniques. However, many practitioners utilise somewhat heuristic or ad hoc methods for input variable selection (IVS) during ANN development.This paper describes the application of a newly proposed non-linear IVS algorithm to the development of ANN models to forecast water quality within two water distribution systems. The intention is to reduce the need for arbitrary judgement and extensive trial-and-error during model development. The algorithm utilises the concept of partial mutual information (PMI) to select inputs based on the analysis of relationship strength between inputs and outputs, and between redundant inputs. In comparison with an existing approach, the ANN models developed using the IVS algorithm are found to provide optimal prediction with significantly greater parsimony. Furthermore, the results obtained from the IVS procedure are useful for developing additional insight into the important relationships that exist between water distribution system variables.     

石墨粒度对低炭镁炭砖性能的影响

以电熔镁砂和4种粒度(≤0.149mm、 ≤0.074mm、≤0.044mm和≤0.01mm)的天然鳞片 石墨为主原料,在石墨含量为4%的条件下,研究了 石墨粒度对低炭镁炭砖的物理性能、抗氧化性和热震 稳定性的影响。结果表明:用细石墨取代较粗石墨 (粒度≤0.149mm)制成的镁炭砖,其物理性能、抗氧 化性和热震稳定性都有了明显的改善,且都以加入粒 度≤0.074mm石墨的效果最好。其原因是细石墨的 加入改善了镁炭砖的基质结构。石　墨     

(Abstracts)Changing Industrial Demands

Abstract

The frequency dependence of discomfort caused by vertical mechanical shocks has been investigated with 20 seated males exposed to upward and downward shocks at 13 fundamental frequencies (1–16 Hz) and 18 magnitudes (±0.12 to ±8.3 ms^?2). The rate of growth of discomfort with increasing shock magnitude depended on the fundamental frequency of the shocks, so the frequency dependence of equivalent comfort contours (for both vertical acceleration and vertical force measured at the seat) varied with shock magnitude. The rate of growth of discomfort was similar for acceleration and force, upward and downward shocks, and lower and higher magnitude shocks. The frequency dependence of discomfort from shocks differs from that of sinusoidal vibrations having the same fundamental frequencies. This arises in part from the frequency content of the shock. Frequency weighting W_b in BS 6841:1987 and ISO 2631-1:1997 provided reasonable estimates of the discomfort caused by the shocks investigated in this study.

Practitioner Summary: No single frequency weighting can accurately predict the discomfort caused by mechanical shocks over wide ranges of shock magnitude, but vibration dose values with frequency weighting W_b provide reasonable estimates of discomfort caused by shocks similar to those investigated in this study with peak accelerations well below 1 g.